Causes of Cerebral Palsy
Cerebral palsy ("CP") is one of the most common causes of motor disability in the United States. Each year thousands of babies and children are diagnosed with CP and an estimated 500,000 people are living with the disorder in the U.S. The underlying cause of cerebral palsy is well understood. Cerebral palsy is the result of a specific type of brain damage occurring while the brain is still forming during fetal gestation, birth or infancy. When cells in the brain are injured during this early formative phase it creates a permanent "glitch" or flaw in the hardware of the individual's brain. This brain glitch is what ultimately causes movement disabilities in people with cerebral palsy.
The brain functions as the control panel for all of the muscle movements of the human body. If you want to move your arm, leg, you use your brain to do it. The brain directs movement of the body by transmitting lightning fast electrical impulse signals. These signals travel over nerve pathways connecting the brain to the various parts of the body. Each impulse signal from the brain gives specific instructions to the muscles on what to do. With cerebral palsy, the glitch in the brain impairs its ability to generate and transmit the normal impulse signals that control body movements. Instead of transmitting clear, immediate movement instructions to the muscles, a brain with the CP glitch sends distorted, conflicting and delayed signals. The end result is that the individual with CP cannot properly control and coordinate movements of certain muscles in their body. Although they may look deformed, there is actually nothing structurally wrong with the muscles in the affected parts of the body. The abnormality is actually inside the person's brain.
Causes of Brain Damage Resulting in Cerebral Palsy
Cerebral palsy is ultimately caused by a particular type of damage to the brain occurring while the complex inner workings of the brain are still forming. The window of time for this damage to occur is from about week 20 of pregnancy to the first 6 months of life. Any damage to the brain during this time frame can potentially lead to cerebral palsy. The particular cause of the damage to the developing brain can vary. Any trauma, health condition, or event that kills or damages cells in the brain during this time can be the trigger. During childbirth oxygen deprivation and head trauma are primary causes. When the brain is damaged during gestation pregnancy complications or infection are the most likely reasons.
Brain Damage During Pregnancy
Infections: certain types of maternal infections during pregnancy can disrupt the supply of oxygen and nutrients to the baby or directly attack the womb. Both scenarios can cause damage to cells in the fetal brain. Recent studies have shown that infections during pregnancy are actually one of the more common causes of cerebral palsy.
Prenatal Asphyxiation: when the supply of maternal oxygen to the fetus is restricted or cut off for any prolonged time period, cells in the baby's brain will rapidly start to die. This type of hypoxic brain injury is a leading trigger for CP. Fetal oxygen deprivation during pregnancy can be caused by a variety of prenatal complications, particularly those involving the placenta or umbilical cord.
Genetic Abnormality: a small percentage of CP cases are caused by genetic conditions which cause the brain to develop abnormally during gestation. These inherited conditions can disrupt prenatal cell migration and myelin development which has the same effect as damage to brain cells.
Brain Damage During Childbirth
Oxygen Deprivation: deprivation of oxygen during labor and delivery is the most common cause of cerebral palsy. The human brain requires a continuous supply of oxygen to survive. If oxygen to the brain is stopped or restricted for any extended time period brain cells will rapidly start to die from oxygen starvation. Until they start breathing on their own, babies are reliant on the maternal oxygen through the placenta and umbilical cord. However, during labor and childbirth this fetal oxygen delivery system is particularly vulnerable to interruption. Almost any delivery complication or prolonged delay during childbirth can potentially deprive the baby of oxygen and damage the brain. Delivery complications involving the placenta (e.g., placental abruption) or umbilical cord (e.g., umbilical prolapse or cord knots), are particularly threatening to the fetal oxygen supply.
Head Trauma: traumatic physical injury to the baby's head during a difficult vaginal delivery can lead to internal damage or conditions affecting the baby's brain. This can destroy cells in the baby's brain and result in cerebral palsy. External trauma to the baby's head can because caused by the mother's pelvic bone. However, the far more common source of head injuries during delivery are birth assistance tools such as obstetric forceps and vacuum extractors. Doctors use these devices to grip the baby's head and manually maneuver it through the birth canal. When not used with extreme care, however, these tools can and frequently do damage the baby's head. In some cases this type of external head trauma can cause complications that injure the brain.